I met someone who is also HIV positive and on treatment -- I am too. We always use condoms during sex, but I have also been eating his semen. Last night I had night sweats like I used to have before I found out I was positive. Is it possible I've been re-infected with his strain of HIV? Can I get drug resistance because of it? We both have had an undetectable viral load for a long time and have high CD4 cell counts (over 900), so is there anything to worry about?
Thank you for writing in with a common and often confusing subject. Doctors have speculated on the possibility of a "superbug" or a "superinfection" since HIV was discovered in the 1980s. But are these concerns legitimate and valid in real-world situations?
The answer to that is surprisingly murky and scientifically unclear. The Centers for Disease Control and Prevention tells us that HIV superinfection is rare, happening less than 4% of the time. Some researchers argue that although superinfection can technically occur, actual incidence has only been seen in about 16 people who were re-infected -- and that was mostly through IV drug use, not sex.
I remember, when I started working in HIV prevention in 1991, we were recommending all HIV-positive people make sure they use condoms with all HIV-positive partners. When combination antiretroviral therapy became widely available in 1996, we were instructed that people living with HIV still had to use condoms with each other, or else a strong, untreatable supervirus would inevitably emerge and make HIV impossible to treat in the years ahead.
By 2000, it was pretty clear that (1) people living with HIV were not using condoms with each other and yet (2) no supervirus had emerged. Despite folk myths to the contrary, and a very offensive episode of Law & Order: Special Victims Unit in 2005, the reality is that HIV strains have remained treatable and medications are continuing to save lives.
The most relevant issue here, however, is that no person living with HIV who is virally suppressed for six months or longer can transmit HIV sexually to another person -- that includes to their own sexual partners who are also living with HIV. So even if there were some concern about being in that theoretical less-than-4% of people who are at risk of developing drug resistance from condomless sex, all of that risk would be brought down to zero based on the fact that your partner cannot transmit HIV to you, or anyone, when they are undetectable.
The next most relevant issue here is that oral sex is considered to be "little to no risk." Even if your partner had a detectable (i.e., potentially transmittable) HIV viral load, the possibility of acquiring a superinfection from oral sex is pretty much zero (or "negligible"). This is because oral sex, with ejaculation, is not considered to be an activity that would put anyone at risk of encountering HIV as long as they have basic dental hygiene.
I don't know the cause of your night sweats; only a medical professional who sees you in person can tell you accurately. But quite often, when we worry about getting HIV symptoms, we manifest those symptoms. I know before I started using HIV pre-exposure prophylaxis (PrEP), I would regularly wake up with night sweats and swollen lymph nodes, and I would scan my body for any purple spots that didn't used to be there. Once I learned the science and efficacy behind PrEP, and began taking it, then the anxiety went away, and so did the sweats. Again, I'd encourage you to talk to a doctor about these symptoms, and perhaps consider if a knowledgeable therapist in your area might be able to help as well.
I hope this information allows you to relax, enjoy, and know that by taking your HIV medications and staying undetectable you are doing everything in your power to ensure a long and sexually fulfilling life for yourself and your partners.